JPS61292599A - Vessel for radioactive waste - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a radioactive waste product for sealed management of radioactive waste such as waste after spent fuel reprocessing as cement assimilated material, glass assimilated material, etc. Regarding containers.

(Technical background of the invention and its problems) The waste after reprocessing spent fuel contains heavy nuclei that emit neutrons and alpha rays, such as PU and cm, so it has a long half-life.
Since it contains hazardous substances, its management is important. As a method for quantifying these nuclides in waste, as shown in Fig. 4, a plurality of holes are provided inside a side wall 1 made of a material such as polyethylene that surrounds a container A for solidified waste, and these holes are There is a passive neutron method in which a neutron detector 3 is inserted into the waste material and neutrons emitted from the solidified waste are measured.

This method is suitable for detecting the amount of neutrons emitted from the waste assimilate near the neutron detector 3. However, as is clear from FIG. 5, which shows the relationship between the sensitivity of the neutron detector 3 and the position of the neutron source, the accuracy of quantifying alpha radioactivity such as pu and cm becomes extremely poor as the area approaches the center of the container. . In addition, when mononuclei in the solidified waste are unevenly distributed, there is a problem in which the accuracy of quantifying the mononuclear in the solidified waste is extremely low.

[Purpose of the invention]

The purpose of the present invention is to prevent neutrons, etc. from radioactive waste when managing radioactive waste, such as waste after reprocessing spent fuel, as a cement solidified material, vitrified material, etc. in a sealed container. An object of the present invention is to provide a container for radioactive waste that can accurately detect radiation and safely manage radioactive waste.

[Summary of the invention]

The present invention provides a radioactive waste container for sealing a solidified radioactive waste, in which at least a space for installing a radiation detector into which the assimilated material is embedded from the surface of the container is kept sealed from the outside with respect to the solidified material. This is a container for radioactive waste characterized by the following:

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a perspective view showing a radioactive waste container according to the present invention, and FIG. 2 is a sectional view taken along line A-A in FIG. 1.

1 and 2, a container 5 is filled with solidified radioactive waste after reprocessing spent fuel. The container 5 has a bottom surface extending in the height direction of the container 5,
Three spaces 6 are formed at predetermined intervals. The spaces 6 are each provided in a state in which the container 5 is kept sealed. A neutron detector 7 is installed in each of these spaces 6. In such a container for radioactive waste, the neutron detector 7 is installed approximately in the central area of the solidified body of radioactive waste 5 and in the surrounding area. FIG. 3 shows the relationship between the distance from the center of the container 5 and the sensitivity of the neutron detector 7.

As is clear from FIG. 3, the sensitivity is high in the center region of the container 5, and the sensitivity decreases from the center region of the container 5 toward the side wall of the container 5, but the rate of decrease is extremely small.

In this embodiment, an example of three columnar spaces is shown as the space 6, but the number of spaces can be arbitrarily selected depending on the size of the solidified body. Furthermore, the space is not limited to extending from the bottom of the container in the height direction of the container, but may extend from the side wall of the container in the axial direction of the container.

Furthermore, a plurality of neutron detector holes may be provided in the side wall of the container as shown in FIG. 1 together with the space shown in FIG. 3, and the neutron detectors may be installed in these holes. In this case, a sensitivity curve is obtained by combining the sensitivity curves shown in FIGS. 2 and 5, and the neutron constant fft1 degree is further improved regardless of the bias in the distribution of Pu, Cm, etc. in the solidified body.

In the present invention, the detector installed in the space is not limited to a neutron detector, but may be any detector that can detect radiation emitted from radioactive waste. Moreover, the radioactive waste is not limited to nuclear fuel reprocessing waste, but may be any waste that can be stored as a solidified substance in a container.

[Effect beam of invention]

As described above, according to the present invention, it is possible to detect neutrons, gamma rays, etc. emitted from solidified bodies of radioactive waste with high sensitivity, and even when the solidified body is large, a detector is placed near the radiation source area. Since a detector is installed, the accuracy of mononuclear quantification can be improved by detecting neutrons, gamma rays, etc.

[Brief explanation of drawings]

Fig. 1 is a partially transparent perspective view of a container for radioactive waste according to the present invention, Fig. 2 is a sectional view taken along the line A to Fig. 1, and Fig. 3 is the center of the container in Fig. 1. A graph showing the relationship between the distance from the area and the sensitivity of the detector; FIG. 4 is a perspective view of the main parts of a conventional radioactive waste container partially transparent;
FIG. 5 is a graph showing the relationship between the distance from the center region of the container in FIG. 4 and the sensitivity of the detector. DESCRIPTION OF SYMBOLS 1... Container side wall, 2... Hole, 3... Neutron detector, 5... Container, 6... Space part, 7... Neutron detector. 2nd diagram Tea 4yo Figure 5

Claims (1)

[Claims] 1. In a radioactive waste container for sealing a solidified body of radioactive waste, at least a space for installing a radiation detector that is embedded in the solidified body from the surface of the container is sealed from the outside with respect to the solidified body. A container for radioactive waste characterized by being provided in a state where its properties are maintained. 2. The radioactive waste container according to claim 1, wherein the radiation detector is a neutron detector. 3. The radioactive waste container according to claim 1, wherein the radioactive waste is waste after reprocessing nuclear fuel.